Science in China: Earth Sciences published on the cover of an article. Photo courtesy of Institute of Paleovertebrate Vertebrate, Chinese Academy of Sciences
BEIJING, Nov. 1 (Xinhua) -- Grass carp, one of China's famous "four big fishes" and the most commonly used ingredient in "boiled fish", diners may not care when and where it originated when tasting delicious food, but it is very important for paleontologists and is closely related to paleoenvironmental research.
Related grass carp pharyngeal bone and its pharyngeal teeth, row teeth and other seedling sweeping diagrams. Photo courtesy of Institute of Paleovertebrate Vertebrate, Chinese Academy of Sciences
Chinese scientists have speculated that grassfish originated from a carnivorous fish in western China in the early Oligocene about 30 million years ago, which was a temperate grassland environment that was not much different from the habitat of grass carp at that time, which was a temperate grassland environment and is not much different from the habitat of today's grass carp. Modern grass carp has been formed since the Pliocene, about 5.3 million years ago.
a Sansheng Gongde-made fish (new species of new genus); b Liu's grass carp (new genus of new species); c Xiejia grass carp (new species) ;d Oriental grass carp (new species). Photo courtesy of Institute of Paleovertebrate Vertebrate, Chinese Academy of Sciences
This paper on the evolution and spatio-temporal distribution of throat teeth of grass fish and its paleoenvironment since the Cenozoic Era was jointly completed by Su Ruifeng, associate researcher of the Beijing Institute of Life Sciences of the Chinese Academy of Sciences, Academician Zhang Miman of the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, and Chen Gengjiao, a researcher of the Guangxi Museum of Natural History, and published in the latest issue of "Science in China: Earth Science" in english and Chinese editions in the form of cover articles, systematically studying the evolution of pharyngeal teeth of grass carps since the Neogene period in eastern China. Spatial-temporal distribution and explore its paleoenvironmental significance.
Grass carp "comb" throat teeth are distinctive
According to the research team, the history of grass carp being eaten in China can be traced back to the Yin Shang era, and its current species are naturally distributed in eastern China, and as a "worker" for eating or cleaning water bodies and grasses, it has long been imported into many countries and has attracted much attention.
Grass carp's distinctive comb-shaped throat teeth allow it to feed heavily on larger plants in water bodies. Grass carp and other carps have no teeth at the mouth margin, only throat teeth growing on a pair of throat bones inside the gill lid. Grass carp has two rows of pharyngeal teeth on each of the two throat bones to the left and right, with 4 or 5 pharyngeal teeth on the first row being larger, and the pharyngeal teeth on the second row being very small. Each of its pharyngeal teeth has a long neck, the anteroposterior and posterior sides of the crown are flattened, and the two sides of the chewing surface on the crown have ridges and grooves arranged in a parallel oblique direction, presenting a perfect "comb" shape. As a unique genus of carps, grass carp derives its scientific name from this comb-shaped throat tooth.
The surface of the pharyngeal teeth of grass carp is enamel and very hard. The old pharyngeal teeth wear out during continuous feeding, and then new pharyngeal teeth grow out to replace them. The pharyngeal teeth buried in the formation after wear and tear are made a very valuable material for studying the evolution of carps. This unique comb-like pharyngeal tooth of grass carp has been found in multiple Cenozoic formations in China.
Through further research, the research team found that the comb pharyngeal teeth of grass carp fossil teeth with ridges and grooves on the crown have appeared in the Early Oligocene formation 30 million years ago, which is significantly different from the shape of the pharyngeal teeth of modern grass carp. Up to now, grass carp comb pharyngeal fossil material has appeared in 22 sites at the Sites of early and late Oligocene, Early Miocene, Miocene, Miocene, Late Miocene, Pliocene, Pleistocene and Paleoanthropologist sites.
Fossil studies suggest that the modern grass carp has formed in the Pliocene
Among the 22 fossil material sites, the research team found that the throat fossils from the two sites of the Oligocene represented two relatively ancient extinct species, and established the "Sansheng Gongde Fish" of the genus Dezou and the "Liu's Grass Fish" of the genus Bedrock.
Among them, the Sansheng Gongde fish of Hangjinhou Banner in Inner Mongolia, the ridge and groove on the side of its crown are relatively short, the tip is curved and enlarged, the chewing surface is narrow and long and straight, and the end tip of the ridge makes the edge of the chewing surface serrated. This jagged chewing edge is common in juvenile grass carps that have just sprouted teeth, but have not been found in the pharyngeal teeth of adult grass carps.
The genus Of the genus Primordial grass carp was collected from Anci, Langfang, Hebei Province, and its throat tooth morphology is closer to that of the living grass carp, but the teeth are thicker and shorter, the number of lateral ridges before and after the crown of the teeth is small and short, the lateral end of the chewing surface seems to turn later, and the fossil represents the extinct genus of grass-like fish.
In addition, a large number of throat teeth collected from the Miocene represent two extinct species of the genus Grass Carp, the Xiejia Grass Carp and the Oriental Grass Carp. The throat teeth of the Xiejia grass carp in Qinghai Huang have both the main and second rows of teeth, and their main teeth are significantly more numerous than those of Sansheng Gongde and Liu's grass carp, and the grooves between the ridges are narrower, and the adult fish teeth chew on the surface without the end of the pointed ridge. However, compared with the pharyngeal teeth of the living grass carp, the crown of the pharyngeal teeth of the Xiejia grass carp is thicker, the ridge is also thicker, shorter and less, the tooth handle is not significantly thinned at the boundary with the tooth crown, the groove between the ridge is wider than that of the grass carp, and the ridges on the front and back sides are almost perpendicular to the chewing surface.
Oriental grass carp comes from Sihong, Jiangsu, northern Inner Mongolia and Lantian, Shaanxi, and its large number of comb-shaped throat teeth are more similar to grass carp, mainly manifested as: the tooth handle is significantly narrower than the crown of teeth; the number of ridges and grooves is more, the ditch is narrower; the ridge and groove are longer, and its length is equal to or even slightly longer than 1/2 of the height of the crown, especially the ridge and groove located in the middle of the crown. However, the morphology of these pharyngeal teeth is still significantly different from that of grass carp, such as the number of ridges and grooves is still significantly smaller, and the length is significantly shorter.
The research team pointed out that the pharyngeal teeth of grass carp that have appeared in various strata since the Pliocene are exactly the same as those of modern grass carp, indicating that modern grass carp has formed from the Pliocene about 5.3 million years ago.
According to the grass carp or grass carp fossils found so far, from the late Oligocene to the Miocene, grass fish spread and migrated eastward, spreading throughout western, eastern and northern China, with a much wider distribution than that of modern grass carp. Since the Pliocene, with the strengthening of the uplift of the Qinghai-Tibet Plateau, the formation of large rivers in East Asia flowing eastward into the Pacific Ocean, and the strengthening of summer winds in Asia, the distribution of grass fish was eventually limited to the new environment on the east coast of the Pacific Ocean, evolving into a modern species, forming the current life and breeding habits.
Studies speculate that grass fish originated in western China in the early Oligocene
The research team said that the two extinction genera, species and two extinction species of grass carp and the fossil pharynx of modern grass carp in this study broadened the academic understanding and understanding of the evolution of carp endemic to East Asia in time and space, combined with their living and reproductive habits and mammals unearthed at the same site, which can reflect the climate and water environment characteristics of the land point to a certain extent.
The fossil pharyngeal teeth of Sansheng Gongde fish was collected from Inner Mongolia outside the distribution area of the living grass carp, and its morphological characteristics indicate that it does not resemble a plant-feeding fish. Although its relationship with grass fish is not well established, it is speculated that it may be the carnivorous ancestor of grass fish, a site near the northwest corner of the present-day Yellow River Loop, which at the time may have been a temperate steppe environment.
The throat teeth of Liu's grass carp, which are harvested from Anci in the Dagang Oilfield in eastern China, have more morphologically similar characteristics to grass carp, indicating that they have more herbivorous habits and may inhabit a more gentle and moist environment than in the Early Oligocene.
The emergence of The Miocene Xiejia grass carp and Oriental grass carp shows that these grass carp species are closer to living grass carp species. At present, it is only found in the Xiejia Formation in Huangzhong, Qinghai, and the oriental grass carp is found in multiple strata from the middle to late Miocene, many of which are located in the range of modern grass carp distribution.
Thousands of fossil pharyngeal teeth of oriental grass carp in Sihong, Jiangsu Province, as well as the abundant fossils of pharyngeal teeth of other fish in the cyprinid family, suggest that there was a large water environment and its rich aquatic plants at that time, while considering the mammal fossils here, suggesting that the region's early Miocene climate was relatively warm and humid. The discovery of oriental grass carp in the Tongur region of Inner Mongolia shows that there must have been a large enough lake or river in the area at that time, which was very different from the current climate of the local area, which was very different from the environment dominated by short grass grasslands, deserts, sand dunes and high alkaline ponds.
The research team believes that based on the above fossil research content, it can be speculated that grass fish originated from a carnivorous fish in western China in the early Oligocene about 30 million years ago, which was a temperate grassland environment at that time, which was not much different from the habitat environment of grass carp today.
Among the major rivers in eastern China, the Heilongjiang and Yellow River systems have a variety of fish such as grass carp, but there is no record of grass carp in the Liao river system between these two major rivers. The research team pointed out that it is likely that the Liao River once had grass carp distribution, when the Nen River was still in the upper reaches of the Liao River, the city of Changchun between the Nen River and the Liao River and its vicinity in the Quaternary Period was uplifted by the new tectonic movement, and the upper reaches of the Gu Nen-Liao River basin were attacked by the Songhua River, a large tributary of the Heilongjiang River, thus bringing many fish, including grass carp, to the northern Heilongjiang River. However, when the Liao River is separated from its upper reaches, the amount and length of the Liao River can no longer meet the needs of grass carp to survive and reproduce.
The research team said that the evolution of grass fish found in the latest study shows that during the Oligocene, the vicinity of Sanshenggong in western China was a little dry and cold but still warmer than today; during the Miocene, the climate in central Inner Mongolia was also warmer and wetter than it is today; from the Pliocene onwards, the climate and water ecological environment in East Asia became similar to modern times. (End)
Source: China News Network